A capacity of a wireless communications network (e.g. a number of communication devices that may be supported by the network) is generally determined by an acceptable bit error rate (BER), an acceptable signal-to-noise ratio of the communications devices operating within the network, and the type of service (data rate) required by the communication devices. These parameters are often affected by such factors as the amount of noise and interference within the network, multi-paths, distance between the communication device and a transmitting base station, and the transmission power of the communications device.
One technique to increase the number of communication devices that may operate within the network is to allow the individual communications devices to determine the acceptable communications parameters, such as a desired quality of service (QoS), required for a particular transmission of information. For example, the communications device may request a connection to a base station that permits an information transfer rate of 100 kilo bits/second and a maximum time delay of 10 milliseconds in between information packets.
Different kinds of information are transferred through the communications network. Users are aware to varying degrees of a “delay” associated with the transmission of information, as the information, traverses from a first point to a second point within the communications network. Thus, a variety of levels of QoS are provided within the communications network.
Conversational class known in the art as telephony speech is performed between peers of live users. This class of information transfer is subject to human perception because of the real time characteristic inherent in a conversation between human users. Thus, the transfer delay needs to be low because of the conversational nature of this scheme. The limit for acceptable delay is given by the human perception of video and audio conversation. Failure to provide a low enough delay will result in an unacceptable lack of quality. Thus conversational class transmissions have the most stringent requirements for QoS time delay.
Streaming class refers to the transmission of information that occurs when a user is looking at or listening to a real time video or audio broadcast. This is a one way transport of information. It is important that the time alignment between entities (i.e. samples, packets) in the broadcast stream be preserved, however, the streaming class transmission does not have a QoS requirement for a low time delay as does the conversational class.
Interactive class describes the situation that occurs when a user, either machine or human, is requesting information from equipment at a remote site. Some examples of human interaction with the equipment at the remote site are: web browsing, data base retrieval, and server access. Round trip delay time is a key attribute of this type of information transfer. Interactive class information transfer is characterized by the request response pattern of the user, thus the QoS delay requirement is important, approaching the kind of delays users find acceptable with conversational class information transfer.
Background class information transfer occurs when information is sent or received in the background, typically by a computer. Examples of this type of information transfer are E-mails, downloads of data bases, etc. Background transfer of information is characterized by the fact that the destination is not expecting the information within a certain time. Background class information transfer is, in general, time insensitive. However, when multiple classes of information transfer are initiated by a user, such as conversational class and background class (E-mail), it is possible for a large delay in background class information transfer to be perceived as annoying by the user.
In many cases the communication devices are mobile and are powered by a battery. The battery will operate for a finite time before needing to be recharged. What is needed therefore, is a way of extending battery life by reducing the power required to transmit information from the communication device within the constraints imposed by QoS requirements on the transfer of information.